Knock-out for junction boxes and the like



June 12, 1934. MANG|N 1,962,317

KNOCK-OUT FOR JUNCTION BOXES AND THE LIKE Filed Feb. 26, 1932 I c/ames /7w ,5):

orweys Patented June 12, 1934 KNOCK-OUT FOR JUNCTION BOXES AND THE LIKE James Mangin, New Brunswick, N. J assignor to New Brunswick Electric Supply Company, New Brunswick, N. J., a corporation of New Jersey Application February 26, 1932, Serial No. 595,372

3 Claims.

This invention relates to improvements in knock-outs for electrical junction boxes and like articles. As is well known, it is customary to provide one or more of the walls of junction 5 boxes with knock-out portions which may be a tool from either side of the box wall, thus enabling a workman to readily remove the knock out from the inside of a box where the box is already installed in a wall or other part of a building,

The above and other objects, as well as the specific features of the invention, will be clearly understood from the following detailed description and the accompanying drawing, in which Fig. 1 is a perspective view of a junction box equipped with the improved knock-outs of the invention; and

Fig. 2 is a perspective View of one of the knockouts after its removal from the box.

Referring to the drawing and particularly to Fig. 1, there is illustrated a junction box 1 which takes the customary form of such boxes. The walls of box 1 are provided with a desired number of knock-outs 2 which are similar to those used heretofore in that they are defined by a single line of rupture 3 interrupted by a single intact portion 4. As will be clearly understood, the metal is weakened along line 3 and the knock-out is held by the intact portion 4.

In accordance with the present invention, knock-outs 2 are formed with an integral raised strap 5 by pressing or striking a central strip of the material of the knock-out outward from the plane thereof. The knock-out may be formed by a single stamping operation which also forms the line of rupture 3. While the strap may be located in any desired position relative to intact portion 4, I prefer to form the strap so that it is substantially aligned longitudinally with the intact portion. When thus formed, the knock-out may be more readily removed when a tool is inserted beneath the strap than would be the case if the strap were located otherwise relative to the intact portion. This will be clearly apparent to persons skilled in the art from a visualization of the action which takes place when a tool is inserted beneath the strap and the extending end of the tool is raised to pry the knock-out loose from the box. The tendency is not so much to bend the intact portion 5 but to twist or shear it.

The structure of the lsnoclnouts described above results in the provision of a slot 6 beneath strap 5 and a second slot '7 in the body of the knock-out, the latter slot resulting from 651 the removal of the material forming the raised strap. In the illustration of Fig. 1, it will be apparent that the knock-out may be removed from the outside of the box by the insertion of a tool in slot 6. It will be also apparent, however, that the knock-out may be readily removed from the inside of the box by the insertion of a tool in slot 7. Thus the particular form of knock-out contemplated by the invention provides two distinct slots which enable the removal of the knock-out from either side of the box wall. Although the illustration of Fig. 1 shows the raised strap as extending outside the box, it will be obvious that the strap may be formed so as to extend inside the box.

It is important to note that the improved knock-out of this invention may be removed by the mere twist of a tool, such as a screw driver, which has been inserted in either of the slots above mentioned. By virtue of the disposition 8.5 of the slots relative to the intact portion of the knock-out, the mere twisting or turning of the tool will cause rupture of the intact portion. This becomes increasingly important when it is considered that in many instances where the box is already installed, sometimes at a considerable distance from a wall surface, it is very difficult to remove a knock-out due to lack of room for manipulation of a tool. Oftentimes, it is impossible to exert a prying force and kncclbouts requiring this cannot be readily removed. It is always possible, however, to inserta tool into the knock-out and to twist or turn the tool, as simply required in using my device.

From the present disclosure, it will be manifest to persons skilled in the art that the invention provides a simple form of knock-out which may be economically provided but which nevertheless has the desired advantages set forth above. Although the preferred form of the invention has been illustrated herein for the purpose of disclosure, it will be understood that any such modifications in details as come within the scope of the appended claims are deemed to be a part of the invention.

I claim:

1. A metal structure having a Wall, provided with an integral unitary removable portion lying in the plane of said wall, said portion being defined by a single line of rupture interrupted by a single intact portion, said removable portion having a raised strap struck therefrom, whereby a slot is provided beneath said strap, and a second slot is provided in the body of said removable portion, said slots being respectively adapted to receive a tool from opposite sides of said wall for removal of said removable portion.

2. A metal structure having a Wall, provided with a removable portion, said portion being defined by a single line of rupture interrupted by a single intact portion, said removable portion having a raised strap struck therefrom, said strap being substantially aligned longitudinally with said intact portion, whereby a slot is provided beneath said strap, and a second slot is provided in the body of said removable portion, said slots being respectively adapted to receive a tool from opposite sides of said wall for breaking out said removable portion, whereby said portion may be broken out by a twist of said tool.

3. A metal structure having a Wall, provided with a removable portion, said portion being defined by a single line of rupture interrupted by a single intact portion, said removable portion having a raised strap struck therefrom forming slots beneath said strap and in the body of said removable portion for the reception of a tool, said intact portion and said strap being in predetermined relation to each other such that a twist or" an inserted tool will rupture said intact portion.

JAMES MANGIN. 

